argenx SE

Board/Management Information • Jul 16, 2015

arGEN-X N.V. announces change to the Board of Directors

Breda, the Netherlands/Ghent, Belgium, 15 July 2015 - arGEN-X N.V. (Euronext Brussels: ARGX), a clinical-stage biopharmaceutical company focused on creating and developing differentiated therapeutic antibodies for the treatment of cancer and severe autoimmune diseases, today announces that non-executive director Michael B. Sheffery, representing Orbimed Advisors, will resign from the Board of Directors per 26 August 2015.

Mr. Michael B. Sheffery has been involved with arGEN-X B.V. since the venture capital investment of Orbimed Advisors in 2011. The resignation of Mr. Michael B. Sheffery is in line with the company's aim to gradually replace all of its originally investor appointed non-executive directors with independent industry professionals, in accordance with the requirements of the Dutch Corporate Governance Code.

"We would like to take this opportunity to thank Michael for his very important contributions as Director over the past years. We greatly appreciate all he has done to help us develop arGEN-X," commented Peter Verhaeghe, Chairman of the Board of Directors.

ABOUT arGEN-X

arGEN-X combines the diversity of the lama immune system with antibody engineering to advance a clinical pipeline to treat patients with cancer and autoimmune diseases. Our platforms allow us to unlock novel and complex targets and develop antibody-based drugs designed for longer duration of effect and greater efficacy. The strength of our team, our deep understanding of the biology, and our committed collaborations with industry leaders contribute to the success of our journey.

arGEN-X is listed on the Euronext Brussels exchange under the symbol ARGX.

www.argen-x.com

For further information, please contact: Joke Comijn Corporate Communications Manager, arGEN-X +32 (0)477 77 29 44 info@arGEN-X.com

Mark Swallow/David Dible Citigate Dewe Rogerson +44 207 282 2948 arGEN-X@citigatedr.co.uk

Beth DelGiacco (US IR) Stern Investor Relations +1 212 362 1200

Forward-looking Statements

The contents of this announcement include statements that are, or may be deemed to be, "forwardlooking statements". These forward-looking statements can be identified by the use of forward-looking terminology, including the terms "believes", "estimates", "anticipates", "expects", "intends", "may", "will", or "should", and include statements arGEN-X makes concerning the intended results of its strategy. By their nature, forward-looking statements involve risks and uncertainties and readers are cautioned that any such forward-looking statements are not guarantees of future performance. arGEN-X' actual results may differ materially from those predicted by the forward-looking statements. arGEN-X undertakes no obligation to publicly update or revise forward-looking statements, except as may be required by law.